Introduction
The lesson video is the following
Main position
In this lesson we have seen how to invade in the following situation.
The invasion point is at 1, black has two ways to answer. Protect the corner and fight with A or let white into the corner and take the outside with B.
Black keeps the corner
Black can choose to keep the corner with 2.
In this case, both white and black will go out together and it will lead to a fight.
Black keeps the outside
Black can choose to keep the outside with 2.
In this case, black will invade the corner and is sure to live. The sequence up to 12 is the best for both player.
Black can try to be more agressive when white comes in, but it is a mistake as shown below.
In both cases, white can lives, but black outside is less strong than in the previous example.
Finally, it seems natural to go out this way for white, but in this case it would be a mistake.
After the sequence to 12, white position collapse.